The invention relates to an exposure control apparatus for use with a camera having electronic flash controlling capability, and more particularly, to an exposure control system which permits an exposure control to be exercised predominantly based on flashlight from an electronic flash in a daytime synchronized photographing operation in which an object being photographed is illuminated by both natural light and flashlight from an electronic flash.
When taking a picture of an object such as a person standing in a background such as a bright landscape or illumination, a picture is taken of the rear light. Hence, the exposure level will be determined by the bright illumination of the background, resulting in an underexposure. To prevent an underexposure of the object being photographed, it may be illuminated by flashlight from an electronic flash. Taking a picture in a bright illumination by using flashlight from an electronic flash is commonly known as a daytime synchronized photographing operation.
In a photographing operation utilizing a synchronized operation of an electronic flash, the flash is activated to cause a flashlight discharge at the time when the shutter of the camera is fully open. For this reason, an exposure period usable with such camera is generally established on the order of 1/60 second, a relatively slow shutter operation. When the shutter is fully open, the flash is activated in synchronized relationship therewith.
On the other hand, with a camera capable of an automatic exposure control, an exposure control apparatus contained therein is operable to effect photometry of light reflected from an object being photographed to determine a proper exposure period in an automatic manner in order to close the shutter, in any mode of the camera including normal photographing, a photographing operation under the flashlight illumination from an electronic flash and a daytime synchronized photographing operation. However, it will be noted that during the daytime synchronized photographing operation, the electronic flash is activated at the time the shutter is fully open, so that the exposure control apparatus will have been effecting photometry of light from the object under the natural illumination until the flash is activated to produce flashlight, for example, for a time interval of 1/60 second, followed by photometry of light reflected from the object which is now illuminated by the flashlight. In certain circumstances, it is desirable that a picture of the object be taken by an exposure control which is predominantly based on the flashlight from the electronic flash, eliminating the influence of natural light. However, such elimination has been impossible with the prior art arrangement.